Earlier versions of the Rich Communications Suite (RCS) (e.g., RCS BlackBird (BB)) enable a server to check RCS capability of an electronic device of the other party (or an electronic device of a receiving side) and transmit an IP multimedia subsystem (IMS)-based chat message or file.
In RCS 5.x and later versions, since a server supports converged IP messaging (CPM), an electronic device of a transmitting side may only check its own capability so as to transmit an IMS-based chat message or file to an electronic device of a receiving side if the electronic device of the transmitting side is capable of performing RCS transmission. In detail, the server which supports RCS 5.x may transmit, in RCS format, data received from the electronic device of the transmitting side if the electronic device of the receiving side supports the RCS, or may convert the data received from the electronic device of the transmitting side into a legacy message such as a short messaging service (MMS) message or multimedia messaging service (MMS) message using an interworking function (IWF) of the server and then may transmit the legacy message.
FIG. 1A is a diagram of an example of a message transmission environment, according to an embodiment of the present disclosure. More particularly, FIG. 1A conceptually illustrates a process of RCS message transmission in an environment supporting the RCS BB. If a number of a receiving-side electronic device 102 is input to a messaging application of a transmitting-side electronic device 101, the number of the receiving-side electronic device 102 is transferred to a network 100 (e.g., a base station or a server) (stage 1). The network 100 then sends, to the receiving-side electronic device 102, a query on whether the RCS is supported thereby (stage 2), and receives a response to the query (stage 3). The transmitting-side electronic device 101 then obtains, from the network 100, information on whether the receiving-side electronic device 102 supports the RCS (stage 4). Then, the transmitting-side electronic device 101 transmits a message of an RCS format if the receiving-side electronic device 102 supports the RCS or transmits a message of an SMS or MMS format if the receiving-side electronic device 102 does not support the RCS (stage 5). However, the RCS BB method has a limitation in that the transmitting-side electronic device 101 is unable to determine a transmission formation of a message for itself and should be dependent on information received from a server (or the network 100).
FIG. 1B is a diagram of an example of a message transmission environment, according to an embodiment of the present disclosure. More particularly, FIG. 1B conceptually illustrates a process of RCS message transmission in an environment supporting RCS 5.x. The transmitting-side electronic device 101 only checks its own RCS support capability, and transmits data in RCS format if it supports the RCS (stage 1). The network 100 sends, to the receiving-side electronic device 102, a query on whether the RCS is supported thereby (stage 2), and receives a response to the query (stage 3). If the receiving-side electronic device 102 supports the RCS, the RCS-format data transmitted from the transmitting-side electronic device 101 may be transmitted to the receiving-side electronic device 101, but, if the receiving-side electronic device 102 does not support the RCS, the network 100 converts the data into a legacy message (e.g., SMS/MMS) format using the IWF and transmits the converted data (stage 4).
However, since a message type, a file type, a file size, etc. that is supported by the RCS format are different from those defined by the SMS/MMS format, conversion failure may occur. For example, file transfer (FT) of a 10 megabyte-file is enabled in the RCS, but a transferable file size may be limited to 1 MB in the MMS, and thus conversion of a file transmitted as an RCS message from the transmitting-side electronic device 101 into the MMS format fails if the size of the file is too large. For another example, the MMS enables attachment of files such as images, videos, etc., but do not support attachment of files of some formats such as xml, ppt, etc. If the transmitting-side electronic device 101 transmits such files using the RCS, conversion of the files into the MMS format fails. As described above, when the server that supports RCS 5.x fails to convert an IMS-based chat message or FT message into a legacy message using the legacy IWF, the server is unable to transmit an error message to the receiving-side electronic device 102 and transmits it to the transmitting-side electronic device 101. When such an error occurs, since there is no definition for retransmitting a message from the transmitting-side electronic device 101, completion of message transmission to the receiving-side electronic device 102 is not ensured.